Panel for constituting sound insulating wall

ABSTRACT

A panel for constituting sound insulating wall is provided with a front plate, a rear plate, and a sound absorbing member put between the plates. The sound absorbing member contains reduced plastic products coated with magnetic material such as magnetic tape and magnetic sheet. The front plate is provided on the sound source side and constituted of a plate having numerous holes. The sound absorbing member is composed of a permeable bag and the reduced plastic products in the bag so that the bulk specific gravity and permeation resistance can be 0.05-0.4 and 3-90 dyn.S/cm 4 , respectively. The reduced plastic products may be reduced plastic products alone not subjected to other processings, or may be a mixture of reduced plastic products and molded bodies of reduced plastic products. Alternatively, only molded bodies of reduced plastic products can be put in the permeable bag. Therefore, an inexpensive panel for constituting sound isolating wall which has an excellent sound absorbing characteristic, a moisture resistance, a water resistance, and a light weight can be fabricated by utilizing plastic products coated with magnetic material such as magnetic tape and magnetic sheet, and particularly scrap of plastic products.

FIELD OF ART

The present invention relates to a panel for constituting soundinsulating wall used for noise-control measures in locations such asroad, railroad, and the industrial facilities, and in more detailrelates to a panel for constituting sound insulating wall utilizing aplastic coated with a magnetic material such as a magnetic tape ormagnetic sheet, particularly waste material of the same.

DESCRIPTION OF THE PRIOR ART

The amount of production of plastic coated with a magnetic material suchas magnetic tape and magnetic sheet has been increasing year by year.The disposal of that type of refuse has in particular become a problem.At the present time, magnetic tape has been dealt with by burying orburning on the scale of several hundred tons per month all over thecountry.

In the future, if the recovering system of used magnetic tape fromgeneral user is built up, the disposal of that type of the huge amountof refuse will become a problem.

On the other hand, as sound absorbing members, there have been knownfibrous sound absorbing members such as glass wool and rock wool, metaltype sound absorbing members such as aluminum and ceramic type poroussound absorbing members. Also, concrete materials have a sound absorbingperformance. Further, also sheet materials such as plywood, gypsumplaster board, and particle board are used as sound absorbing members.Also, for the purpose of improving the sound absorption property ofspecific frequencies, perforated sheets etc. have been used.

As a panel for constituting sound insulation wall, fibrous soundabsorbing members such as glass wool and rock wool attached betweenfront plate and rear plate have been used.

However, the fibrous sound absorbing members such as the aforesaid glasswool and rock wool have a moisture absorption property and waterabsorption property. As the amount of absorbed moisture and amount ofabsorbed water increase, the sound absorption performance is reduced.Also, in general, sound absorbing members of ceramics and concretes areheavy and expensive, and therefore are not preferable to be used as apanel for constituting sound insulating wall. Also, simple sheetmaterials and perforated sheets generally have a low sound absorptionperformance, and cannot be used as a panel for constituting soundinsulating wall.

SUMMARY OF THE INVENTION

The present inventor has been engaged in repeated studies in variousareas regarding a panel for constituting sound insulating wall which isexcellent in sound absorption performance, excellent also in moistureresistance and waterproofness, and cheap. Consequently he has discoveredthat a panel for constituting sound insulating wall obtained byshredding or pulverizing (collectively referred to in this specificationas "shredding") waste plastic coated with a magnetic material such asmagnetic tape or magnetic sheet coated with, for example, a magneticpowder; and shaping the shreds into a sheet or a block in the panel justas it is, or accommodating shreds with appropriately filling them in abag, exhibits a good sound absorption performance. The excellent soundabsorption is due to the appropriate void proportion and the elasticityof the magnetic tape film, and to its large local surface density. Thisproduct has also excellent characteristics in its moisture resistanceand waterproofness due to a fact that it is a plastic. Thus the presentinvention has been perfected.

The present invention has been made in consideration with such an actualcircumstance and has as an object thereof to obtain a panel forconstituting sound insulating wall, which has a good sound absorptioncharacteristic and in addition is excellent in moisture resistance andwaterproofness, and also a light weight and cheap by utilizing a plasticcoated with a magnetic material, such as magnetic tape or magneticsheet, particularly utilizing the waste thereof.

To achieve the above-mentioned object, a panel for constituting soundinsulating wall related to this invention comprises a front plate, arear plate, and a sound absorbing member attached between these frontplate and rear plate. Said sound absorbing member features to besubstantially constituted of shreds of a plastic coated with a magneticmaterial such as magnetic tape or magnetic sheet.

Preferably said front plate has been provided on the sound source sideand constituted of perforated plate formed with the numerous holes. Asperforated plate, for example, plate made of metal such as aluminumplate having numerous holes of 3 to 50 mm in diameter with the pitch of5 to 100 mm can be preferably used. Inside front plate, woven fabric ornonwoven fabric may be spread. As woven fabric, for example, woven glassfabric of plain weave can be preferably used.

Said rear plate is not particularly limited, but metal plate such asaluminum, galvanized plate and stainless steel plate, plastic moldedplate, of plastic molded plate filled with filler of metal powder orglass fiber, etc. can be used.

Sound absorbing member attached between said front plate and rear plateis preferably comprised of a gas permeability bag and shreds of aplastic coated with a magnetic material accommodated in this gaspermeability bag so that a bulk specific gravity becomes 0.05 to 0.4 anda gas permeation resistance becomes 3 to 90 dyn.S/cm⁴. Shreds of aplastic coated with a magnetic material accommodated in the gaspermeability bag may be shreds alone not subjected to other processingsthan shredding, or may be a mixture of these shreds and shaped articleof shreds. Alternatively, only shaped article of shreds can beaccommodated in the gas permeability bag. The shaped article of shredsis mentioned later.

It is also possible to fill the shreds in the gas permeability bag inlayers or fill the same at random. Moreover, so as to uniformly fill thesame, it is also possible to arrange honeycomb-shaped, circular, etc.partition plates in the interior of the gas permeability bag and to fillthe shreds between these partition plates. As the gas permeability bag,which is not particularly limited, a plastic film, woven fabric,nonwoven fabric (for example, a polyester nonwoven fabric), etc. or acomposite of them can be used.

As a magnetic tape of plastic coated with a magnetic material, an audiotape, video tape, computer tape, and so on can be exemplified. Also, asa magnetic sheet, a floppy disk etc. can be exemplified. A magnetic tapeis constituted by a magnetic layer, base film and a back layer, butthere also exist tapes having no back layer. The magnetic layer isconstituted by a magnetic powder using iron oxide, metal, bariumferrite, or the like; a binder using a vinyl chloride resin,nitrocellulose, polyurethane resin, polyester resin, or the like; and inaddition a cross-linking agent, lubricant, polishing agent, antistaticagent, etc. As the magnetic layer, there also exists one having amulti-layer structure. Moreover, a part of the multi-layer may beconstituted by a layer using a non-magnetic filler.

As the base film, a polyester film is frequently used. Moreover, also apolyethylene-naphthalate film, polyaramide film, etc. is used. The backlayer is constituted by a carbon black powder etc.; a binder such asthat used for the magnetic layer; and an additive.

It is sufficient if the magnetic tape used in the present invention hasa structure of a magnetic layer superposed on a base film. The backlayer may further be provided or not provided. Also, the materials usedfor each of these are not critical.

The shreds of the plastic coated with a magnetic material is obtained byprocessing waste, such as for example magnetic tape or magnetic sheet,by a shredder such as a rotary cutter. The size of the shreds isdetermined by the size of the mesh of the screen provided in the rotarycutter and is not particularly restricted, but preferably the size isabout 2 to 20 mm in length (or diameter).

Also, as the shreds, pieces obtained by shaping the magnetic tape or themagnetic sheet in advance into a concave convex shape and then shreddingit can be used, and also mixtures of pieces obtained by shaped it into aconcave-convex shape and then shredding and pieces obtained by merelyshredding it may be used. So as to obtain the concave-convex shape, atape or a sheet is inserted between a convex mold and a concave mold andpressed. It is also possible to perform the pressing by a flat mold orusing a roll-shaped mold so as to continuously perform the molding.

Moreover, it is also possible that at least a part of said shreds mayconsist of curled shreds which have been curled by heat-treatment. A"curl" in this context means a shape which is approximately circular inwhich the two ends lift up in the case of for example short shreds ormeans wrinkled wavy shreds in the case of long shreds. So as to curl theshreds, generally in the case of a magnetic tape using a polyester resinas the base film, it is sufficient if the shreds are exposed to anambient temperature of 100° to 150° C. The heating conditions can beappropriately set according to the shape of the shreds, amount treated,etc. By curling the shreds, a complex fine pore shape is obtained incomparison with simple shreds. Further, a sound absorbing member havinga small bulk specific gravity can be easily obtained.

Said sound absorbing member also can be constituted of an article shapedby adding a binder into the shreds of a plastic coated with a magneticmaterial so as to have a bulk specific gravity of 0.05 to 0.4 and a gaspermeability resistance of 3 to 90 dyn.S/cm⁴. A shaped article isobtained by mixing a filler with shreds prepared by cutting or shreddingand shaping the same into a sheet or a block using a binder such as alatex or the like mentioned later. The filler for obtaining the shapedarticle is not particularly limited, but a filler such as pulp, sawdust, or inorganic filler material can be used.

So as to obtain a preferred sound absorption performance, it isdesirable to set the bulk specific gravity of the article shaped fromthe shreds or the filled shreds within a range of 0.05 to 0.4. and setthe gas permeation resistance of the article shaped from the shreds orthe filled shreds within a range of 3 to 90 dyn.S/cm⁴. In general, themechanism of the sound absorption can be explained as follows: when asound wave enters into the sound absorption body, the air in the finepores vibrates. At this time, friction occurs between the air and innerwall surfaces of the fine pores, so the acoustic energy is converted toheat energy and absorbed.

If the bulk specific gravity is 0.05 or less or the gas permeationresistance is 3 dyn.S/cm⁴ or less, the resistance is too small, andtherefore even if friction is caused with respect to entry of a soundwave, it is very small. Also, if the bulk specific gravity is 0.4 ormore or the gas permeation resistance is 90 dyn.S/cm⁴ or more, a statewhere fine pores are closed is exhibited, and therefore a sound wave ishard to enter, and friction is hard to be caused. Accordingly, apreferable sound absorption performance can be obtained in theabove-described range.

So as to obtain a sheet-shaped or block-shaped article having a bulkspecific gravity of 0.05 to 0.4 and a gas permeation resistance of 3 to90 dyn.S/cm⁴ as a strong aggregate, preferably the shreds are bridgedtogether by a binder. The binder is not particularly limited, but use ismade of, for example, latexes such as acrylonitrile-butadiene copolymer(NBR), vinyl acetate, or vinyl acetate-ethylene copolymer (EVA),styrene-butadiene copolymer (SBR), polyacrylic acid ester, polyurethane,etc.

So as to obtain a shaped article having a constant shape such as asheet, block, or the like from the shreds, it is sufficient to add theaforementioned filler, a binder such as a latex, and, if necessary, aflame retardant material mentioned later to the shreds, blend them usinga liquid such as water, pour the result into a mold, and press to removethe water. The heating temperature at the time of the press drying isnot particularly limited, but is for example 100° C. or more, and thepressing time is about several minutes to several hours.

However, where the shreds used in the present invention are filled intoa gas permeability bag, the amount of the above-described binder can bereduced to a minimum. In certain cases, it is possible to obtain a soundabsorbing member able to withstand usage even using almost no binder atall.

Note that, where a shaped article obtained by shaping shreds into asheet or a block is formed, so as to improve the flame retardantproperty, it is effective that a flame retardation-imparting material,such as hydrated line, aluminum hydroxide, calcium hydroxide, magnesiumhydroxide, antimony trioxide, etc. is added together with theabove-described latex.

If the shreds are shaped into a sheet or a block, the proportion ofincorporation of the shreds, filler, binder and the flame retardantmaterial is not particularly limited, but preferably the amount of thefiller is 0 to 10 percent by weight, the amount of the binder such asthe latex is 10 to 90 percent by weight, and the amount of the flameretardant material is 0 to 50 percent by weight all based on 100 partsby weight of the shreds. It is not always necessary to incorporate afiller or a flame retardant material in the sound absorbing memberincluded in a panel for construction of sound insulation wall of thepresent invention. Also, in the panel for constituting sound insulatingwall of the present invention with the shreds which are filled in a gaspermeability bag and attached in the panel, it is not necessary eitherto use a binder such as a latex.

If the sound absorbing member with the above-mentioned construction isattached between front plate and rear plate, a panel for constitutingsound insulating wall with a preferable sound insulation performance canbe obtained. Note that, in the panel, it is also possible to accommodatenot only the aforesaid sound absorbing member but a spacer constitutedby plastic foam article etc. In the panel, it is also possible to formthe air layer for sound absorption outside the region where a soundabsorbing member comprising said shreds is attached. Preferably a soundabsorbing member comprising said shreds is attached to the sound sourceside in the panel, and preferably a spacer or the air layer for soundabsorption is provided in the opposite sound source side in the panel.

BRIEF DESCRIPTION OF TEE DRAWINGS

FIG. 1 is a cross-sectional view of a principal part of a panel forconstruction of sound insulation material according to one example ofthe present invention.

FIG. 2 is a front view of front plates shown in FIG. 1,

FIG. 3 is a perspective view of rear plate shown in FIG. 1, and

FIG. 4 is a schematic perspective view of sound insulation wall.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An explanation will be made below of a panel for constituting soundinsulating wall according to examples of the present invention, but thepresent invention is not restricted to these examples.

EXAMPLE 1

As shown in FIG. 1., a panel 2 for constituting sound insulating wallrelated to the present example generally has front plate 4 located inthe sound source side and rear plate 6 located in the opposite soundsource side. In the end of rear plate 6, side plate 8 is integrally orseparately provided in order to connect with front plate 4. Where sideplate 8 is provided separately with rear plate 6, these plates areconnected by spot welding or other methods. The end of side plate 8 andthe end of front plate 4 are connected by spot welding, calking welding,rivet connection, or other methods. In the connected portion, suspendedmetal fittings 10 are connected by spot welding etc.

The front plate 4, for example, is constituted by a perforated sheetmade of aluminum with a thickness of 1.0 mm, eand as shown in FIG. 2, isprovided with a lot of pores 12 with a diameter of 15 mm. The pitch ofthe pores is 18 mm in the direction of P₁ in FIG. 2, and 16 mm in thedirection of P₂ and P₃ in FIG. 2. The size of front plate 4 is notparticularly limited, but the height "h" is 520 mm and the width "b" is1960 mm according to this example.

Inside the front plate 4 shown in FIG. 1, whose illustration is omitted,woven glass fabric of plain weave of 155 g/m² is spread.

The rear plate 6, for example, is constituted by galvanized iron platewith a thickness of 1.6 mm. The rear plate 6 shown in FIG. 3, which hasa dimension corresponding to the height and the width of the front plate4, has been formed integrally with side plate 8 in accordance with thepresent example. In the center of the rear plate 6, an inner projection14 which projects in the direction of the inner panel and extends alongthe lengthwise direction of the rear plate is formed. This innerprojection 14 is not always necessary, but it imparts a predeterminedrigidity to the panel 2, and therefore is preferred to be placed.

The thickness "T" of the panel 2 shown in FIG. 1 is not particularlylimited, but according to this example, is 95 mm. In the panel 2surrounded by the front plate 4, the rear plate 6, and the side plate 8,sound absorbing members 15 are arranged in its sound source side, andspacers 16 are arranged in its opposite sound source side. The spacers16, according to this example, are constituted by polyethyene foamarticles with a thickness (t) of 40 mm and a width of 25 mm, and arearranged almost at equal intervals.

The sound absorbing members 15 are fitted between the spacer 16 and thefront plate 4. According to this example, the sound absorbing member 15is constituted by shreds of magnetic tape and a gas permeability baghaving accommodated these shreds. As the gas permeability bag, accordingto this example, nonwoven polyester fabric of 50 g/m² is used. Foursound absorbing members 15, each of which is constituted by the gaspermeability bag having accommodated shreds of magnetic tape, arevertically tied together to form a aggregate within a panel, and both ofthe vertical ends of the aggregate are held by the suspended metalfittings 10.

Note that, around the junction where the rear plate 6 and the side plate8 are placed in the lowest part of a panel 2, drain holes 18 are formed.

The panels 2 with such a construction, as shown in FIG. 4, arevertically and longitudinally assembled so that the front plates 4 facesound source side, so as to construct a sound insulation wall 20.

Each sound absorbing member 15 in the present example was produced asdescribed below.

As a plastic coated with a magnetic material, use was made of a magnetictape using a polyester film as a base tape but without a back layer.This was shredded by a rotary cutter, so that shreds having a flakesurface area of about 0.3 cm² were obtained. The shreds were placed in agas permeability bag constituted by nonwoven polyester fabric of 50g/m², and thereby a sound insulation material 15 according to thepresent example was obtained.

In the present example, the above-described shreds were filled insidethe gas permeability bag so that bulk specific gravity was 0.17 and thegas permeation resistance was 8.0 dyn.S/cm⁴. The thickness of the massof filled shreds was about 50 mm. More concretely, in the gaspermeability bag with the internal cubic volume of 24 l (liters), theabove-described shreds with a gross weight of 4000 g were uniformlyfilled, whereby a sound absorbing member 15 was obtained. Note that, themeasurement of the gas permeation resistance was carried out accordingto JIS-A6306.

Six pieces of panel 2 according to the present example were used andassembled to a sound insulating wall with sealing the clearances betweenthe panels with the seal materials of the putty. The amount ofpermeation loss was measured in accordance with "Sound permeation lossmeasurement method in the laboratory of JIS A 1416", and the result was34.1 dB as shown in table 1.

Also, the panel 2 according to the present example was used and theamount of the reflection reducing sound was measured in accordance with"The measurement method of the sound absorption rate with thereverberation room method of JIS A 1409", the result was 10.3 dB asshown in Table 1.

                  TABLE 1                                                         ______________________________________                                                       Reflection                                                                              Bulk      Gas                                        Permeation     reducing  specific  permeation                                 loss (dB)      sound (dB)                                                                              gravity   resistance                                 ______________________________________                                        Example 1                                                                             34.1       10.3      0.17     8                                       Comparative                                                                           32.5       9.5       --       --                                      example 1                                                                     Example 2                                                                             33.5       9.5       0.08     4                                       Example 3                                                                             34.2       10.2      0.17     15                                      Example 4                                                                             34.0       10.2      0.17     11                                      Example 5                                                                             34.5       9.8       0.17     10                                      Example 6                                                                             34.5       10.1      0.17     26                                      Example 7                                                                             34.0       10.3      0.17     20                                      Example 8                                                                             35.0       10.6      0.32     30                                      Example 9                                                                             32.1       7.4       0.01*.sup.1                                                                            1*.sup.2                                Example 10                                                                            34.0       7.7       0.5*.sup.1                                                                            100*.sup.2                               Example 11                                                                            32.5       7.6       0.08     1*.sup.2                                Example 12                                                                            33.8       7.9       0.3     100*.sup.2                               ______________________________________                                         *.sup.1 shows the bulk specific gravity out of the range of 0.05 to 0.4.      *.sup.2 shows the gas permeation resistance out of the range of 3 to 90       dyn · S/cm.sup.4.                                               

Comparative Example 1

A panel for constituting sound insulating wall was produced by the sameprocedures as those described in Example 1 except that glass wool boardwith 32 kg/cm³ and the thickness of 50 mm wrapped with fluororesin filmof 20 μm was used as a sound absorbing member.

When the amount of the permeation loss and the amount of the reflectionreducing sound were measured using the panel in the same way as inExample 1, each result was 32.5 dB and 8.5 dB respectively.

Evaluation

As a result of studies regarding Example 1 and Comparative example 1, ithas been confirmed that a panel for construction of sound insulationwall of the present example features the sound insulationcharacteristics of at least an equivalent level in comparison with theprior panel for construction of sound insulation wall.

Moreover, any fibrous sound absorbing members such as glass wools havenot been used in a panel of the present example, but the waste ofmagnetic tapes and the like as a sound absorbing member have been used,so the panel is excellent in the moisture resistance and waterproofnessand does not have a problem which glass wools etc. have. The problem isthat as the amount of absorbed moisture and amount of absorbed waterincrease, the sound absorption performance is reduced. By the way, whenthe amount of the permeation loss and the amount of the reflectionreducing sound were measured by putting the panel according to thecomparative example 1 in the rainwater for a day, each amount could getonly less than half rates of that before putting in the rainwater.Moreover, when once glass wools absorbe water, it is difficult to putits sound absorption performance back. On the other hand, the panelaccording to the example 1 returned to the original situation in a shorttime under the rainwater in the same way as those described above, andalso the result of the measurement was almost the same as the originalrate. Also, the panel of the example can use the waste etc. of magnetictape, so reutilization of refuse resources can be attempted, and thepanel is excellent from a point of view with the recycle of resourcesand the global environment.

EXAMPLE 2

A panel was produced by making sound absorbing member 15 and attachingit in the panel in the same procedures as those described in Example 1except that the shreds used in Example 1 were filled in the gaspermeability bag so that the bulk specific gravity was 0.08 and the gaspermeation resistance was 4.0 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 33.5 dB and 9.5 dB as shown in Table 1.

EXAMPLE 3

A panel produced by making sound absorbing member 15 and attaching it inthe panel in the same procedures as those described in Example 1 exceptthat the flake surface area of the shreds used in Example 1 was set toabout 3 cm², and the shreds were filled in the gas permeability bag sothat the bulk specific gravity was 0.17 and the gas permeationresistance was 15.0 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 34.2 dB and 10.2 dB as shown in Table 1.

EXAMPLE 4

A panel produced by making sound absorbing member 15 and attaching it inthe panel in the same procedures as those described in Example 1 exceptthat the magnetic tape used in Example 1 was passed through aroll-shaped press, a large number of fine concavities-convexities havinga size of 3 mm were formed in the surface of the magnetic tape, this wasshredded by a rotary cutter, shreds having a flake surface area of about0.3 cm² were obtained, and these shreds were filled so that the bulkspecific gravity was 0.17 and the gas permeation resistance was 11.0dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 34 dB and 10.2 dB.

EXAMPLE 5

Three parts by weight of pulp fiber, 45 parts by weight of NBR latex,and 5 parts by weight of flame retardant material constituted byhydrated lime based on 100 parts by weight of the shreds used in Example1 were mixed using 700 parts by weight of water, the liquid mixture waspoured into a mold, and a pressurizing force of 30 kg/cm² was applied toperform the shaping, whereby a shaped article of a sound absorbingmember having the bulk specific gravity of 0.17, the gas permeationresistance of 10.0 dyn.S/cm⁴, and a thickness of 50 mm was obtained.This shaped article of a sound absorbing member was placed in the panelinstead of sound absorbing member 15 shown in FIG. 1, and a panel wasproduced in the same way as in Example 1.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 34.5 dB and 9.8 dB as shown in Table 1.

EXAMPLE 6

A panel was produced by making sound absorbing member 15 and attachingit in the panel in the same procedures as those described in Example 1except that the shreds having a flake surface area of about 0.3 cm² usedin Example 1 were heat-treated in an atmosphere of 130° C. to obtaincurled shreds, and these curled shreds were filled in the gaspermeability bag so that the bulk specific gravity was 0.17 and the gaspermeation resistance was 26.0 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 34.5 dB and 10.1 dB as shown in Table 1.

EXAMPLE 7

A panel was produced by making sound absorbing member 15 and attachingit in the panel in the same procedures as those described in Example 2except that the shreds having a flake surface area of about 0.3 cm² usedin Example 1 were heat-treated in an atmosphere of 130° C. to obtaincurled shreds, these curled shreds and flat shreds before the heattreatment were blended with a weight ratio of 1 versus 1, and they werefilled in the gas permeability bag so that the bulk specific gravity was0.17 and the gas permeation resistance was 20.0 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 34.0 dB and 10.3 dB as shown in Table 1.

EXAMPLE 8

A panel was produced by making sound absorbing member 15 and attachingit in the panel in the same procedures as those described in Example 1except that the shreds having a flake surface area of about 0.3 cm² usedin Example 1 were heat-treated in an atmosphere of 130° C. to obtaincurled shreds, and these curled shreds were filled in the gaspermeability bag so that the bulk specific gravity was 0.32 and the gaspermeation resistance was 30.0 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 35.0 dB and 10.6 dB as Shown in Table 1.

EXAMPLE 9

A panel was produced in the same procedures as those described inExample 1 except that the shreds used in Example 1 were filled in thegas permeability bag so that the bulk specific gravity was 0.01 and thegas permeation resistance was 1 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 32.1 dB and 7.4 dB as shown in Table 1.

EXAMPLE 10

A panel was produced in the same procedures as those described inExample 1 except that the shreds used in Example 1 were filled in thegas permeability bag so that the bulk specific gravity was 0.5 and gaspermeation resistance was 100 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 34.0 dB and 7.7 dB as shown in Table 1.

EXAMPLE 11

A panel was produced in the same procedures as those described inExample 1 except that the shreds used in Example 1 were filled in thegas permeability bag so that the bulk specific gravity was 0.08 and gaspermeation resistance was 1 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was respectively 32.5 dB and 7.6 dB as shown in Table 1.

EXAMPLE 12

A panel was produced in the same procedures as those described inExample 1 except that the shreds used in Example 1 were filled in thegas permeability bag so that the bulk specific gravity was 0.3 and gaspermeation resistance was 100 dyn.S/cm⁴.

When the amount of permeation loss and the amount of reflection reducingsound were measured using the panel in the same way as in Example 1,each amount was 33.8 dB and 7.9 dB shown in Table 1.

POSSIBILITIES OF UTILIZATION IN INDUSTRY

The panel for constituting of sound insulating wall related to thepresent invention features a sound insulation performance of at least anequivalent level in comparison with a prior panel for constituting soundinsulating wall, and is excellent in the moisture resistance andwaterproofness, does not have a problem which glass wools etc. have. Theproblem is that as the amount of absorbed moisture and amount ofabsorbed water increase, the sound absorption performance is reduced.Also, the panel of the present invention can use the waste etc. ofmagnetic tapes, so reutilization of refuse resources can be attempted,and the panel is excellent from a point view with the recycle ofresources and the global environment.

Also, the panel of the present invention uses the waste etc. of magnetictapes as a sound absorbing member, so the panel has the light weight andeconomic, therefore it can be used preferably as a panel forconstituting sound insulating wall of road, railroad, industrialfacilities, and so on.

I claim:
 1. A panel for constituting sound insulating wall, comprising:afront plate, a rear plate, and a sound absorbing member attached betweenthe front plate and the rear plate, said sound absorbing membersubstantially constituted by shreds of a plastic coated with a magneticmaterial.
 2. The panel for constituting sound insulating wall as setforth in claim 1,wherein said sound absorbing member comprises a gaspermeability bag containing therein said shreds of a plastic coated witha magnetic material so as to have a bulk specific gravity of 0.05 to 0.4and a gas permeation resistance of 3 to 90 dyn.S/cm⁴.
 3. The panel forconstituting sound insulating wall as set forth in claim 2,wherein saidgas permeability bag is comprised of any one selected from plastic film,woven fabric, and nonwoven fabric.
 4. The panel for constituting soundinsulating wall as set forth in claim 2 or 3,wherein said gaspermeability bag is arranged in the sound source side in the panel, anda spacer is attached to the opposite sound source side in the panel. 5.The panel for constituting sound insulating wall as set forth in claim4,wherein said spacer is comprised of plastic foam article.
 6. The panelfor constituting sound insulating wall as set forth in claim 2 or3,wherein said plastic coated with a magnetic material is selected froma magnetic tape and magnetic sheet.
 7. The panel for constituting soundinsulating wall as set forth in any one of claims 2 or 3,wherein saidsound absorbing member contains shaped article shaped by adding binderinto shreds of a plastic coated with a magnetic material, so that saidshaped article have a bulk specific gravity of 0.05 to 0.4 and a gaspermeability resistance of 3 to 90 dyn.S/cm⁴.
 8. The panel forconstituting sound insulating wall as set forth in any one of claims 2or 3,wherein at least a part of said shreds comprise curled shreds byheat treatment.
 9. The panel for constituting sound insulating wall asset forth in any one of claims 2 or 3,wherein at least a part of saidshreds are shredded to concave-convex shape.
 10. The panel forconstituting sound insulating wall as set forth in any one of claims 2or 3,wherein each of said shreds has a size of 2 to 20 mm in length ordiameter.
 11. The panel for constituting sound insulating wall as setforth in any one of claims 2 or 3,wherein said front plate is providedon the sound source side and comprised of perforated plate havingnumerous holes.
 12. The panel for constituting sound insulating wall asset forth in claim 11,wherein said perforated plate is comprised ofplate made of metal on which numerous holes of 3 to 50 mm in diameterwith a pitch of 5 to 100 mm are formed.
 13. The panel for constitutingsound insulating wall as set forth in claim 11,wherein inside said frontplate, woven fabric or nonwoven fabric is spread.
 14. The panel forconstituting sound insulating wall as set forth in any one of claims 2or 3,wherein said rear plate is comprised of any one selected from metalplate, plastic molded plate, and plastic molded plate filled with thefiller.